Enabling Electrocatalytic N2 Reduction to NH3 by Y2O3 Nanosheet

Subscriber access provided by Kaohsiung Medical University

Kinetics, Catalysis, and Reaction Engineering

Enabling Electrocatalytic N2 Reduction to NH3 by Y2O3 Nanosheet under Ambient Conditions Xianghong Li, Lei Li, Xiang Ren, Dan Wu, Yong Zhang, Hongmin Ma, Xu Sun, Bin Du, Qin Wei, and Baihai Li Ind. Eng. Chem. Res., Just Accepted Manuscript • DOI: 10.1021/acs.iecr.8b04045 • Publication Date (Web): 22 Nov 2018 Downloaded from http://pubs.acs.org on November 23, 2018

Just Accepted “Just Accepted” manuscripts have been peer-reviewed and accepted for publication. They are posted online prior to technical editing, formatting for publication and author proofing. The American Chemical Society provides “Just Accepted” as a service to the research community to expedite the dissemination of scientific material as soon as possible after acceptance. “Just Accepted” manuscripts appear in full in PDF format accompanied by an HTML abstract. “Just Accepted” manuscripts have been fully peer reviewed, but should not be considered the official version of record. They are citable by the Digital Object Identifier (DOI®). “Just Accepted” is an optional service offered to authors. Therefore, the “Just Accepted” Web site may not include all articles that will be published in the journal. After a manuscript is technically edited and formatted, it will be removed from the “Just Accepted” Web site and published as an ASAP article. Note that technical editing may introduce minor changes to the manuscript text and/or graphics which could affect content, and all legal disclaimers and ethical guidelines that apply to the journal pertain. ACS cannot be held responsible for errors or consequences arising from the use of information contained in these “Just Accepted” manuscripts.

is published by the American Chemical Society. 1155 Sixteenth Street N.W., Washington, DC 20036 Published by American Chemical Society. Copyright © American Chemical Society. However, no copyright claim is made to original U.S. Government works, or works produced by employees of any Commonwealth realm Crown government in the course of their duties.

Page 1 of 11 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

Industrial & Engineering Chemistry Research

Enabling Electrocatalytic N2 Reduction to NH3 by Y2O3 Nanosheet under Ambient Conditions Xianghong Li,† Lei Li,‡ Xiang Ren,† Dan Wu,† Yong Zhang,† Hongmin Ma,† Xu Sun,† Bin Du,† Qin Wei,†,* and Baihai Li, †,‡,* Key Laboratory of Interfacial Reaction & Sensing Analysis in Universities of Shandong, School of Chemistry and Chemical Engineering, University of Jinan, Jinan 250022, China ‡ School of Materials and Energy, University of Electronic Science and Technology of China, Chengdu 611731, China †

* Corresponding Author: Qin Wei E-mail address: [email protected]

1 ACS Paragon Plus Environment

Industrial & Engineering Chemistry Research 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

Page 2 of 11

ABSTRACT: NH3 synthesis consumes 1% of the world’s energy, making it a substantial contribution to greenhouse gas emissions. Electrochemical artificial N2 fixation provides a green and sustainable route over the traditional Haber-Bosch process to enable sustainable NH3 synthesis at ambient conditions while requires catalysts for N2 reduction reaction (NRR). Here, we first demonstrate that Y2O3 nanosheet serve as a high-efficiency non-precious metal NRR catalyst. When tested at neutral pH, such Y2O3 nanosheet attains a large NH3 yield of 1.06×10–10 mol s–1 cm–2 and a high Faradaic efficiency of 2.53% at −0.9 V vs. reversible hydrogen electrode with excellent stability and durability. Density functional theory calculations reveal that addition of the first H atom is the potential crucial step, the following hydrogenation steps are feasible and it is easy to release NH3 molecules.

2 ACS Paragon Plus Environment

Page 3 of 11 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


1. INTRODUCTION NH3, an essential ingredient in the ecological cycle, is commonly used as an activated nitrogen building block to produce modern

medicaments, explosives, plastics, dyes, and fertilizers, etc.1–4 It is also an attractive substitute for petroleum featuring carbon neutral and high energy density.5 Most abundant molecular N2, about 78% of the atmosphere, are inactive due to its high N≡N bond energy, no dipole moment and low polarizability,6,7 and the artificial N2 fixation to NH3 is a severe challenge. Industrial-scale NH3 is mostly produced depending on Haber–Bosch process, but the harsh operation condition result in large energy waste and carbon emission.8 Therefore, an environmentally-benign process for sustainable conversion of N2 to NH3 is urgently needed. Electrochemical reduction using proton from water as the hydrogen source can be powered by electricity produced from clean energy, and it is particularly promising for achieving NH3 production directly from N2 and water at ambient conditions.9–11 While this process involves a hinder in N2 activation, crying need active catalysts for N2 reduction reaction (NRR).12–14 Precious metal based electrocatalysts applying to NRR show high performance, but their large-scale application is hampered by the scarcity and high cost.15–17 As such, great attention has focused on exploring non-precious metal (NPM) alternatives.18-25 Metal oxides are easily prepared on a large scale, promising their widespread uses; however, only very limited such catalysts have been reported, including Bi4V2O11/CeO2,19 Fe2O3-CNT,20 and γ-Fe2O3,21 etc. Given the corrosion issues with acidic and alkaline electrolytes, catalyst electrode for ambient N2 reduction electrocatalysis at neutral pH are highly desired, which has been rarely studied so far. Therefore, idenfication of new NPM oxides nanostructures for the electrochemical reduction of N2 to NH3 at neutral pH is still of immense importance. Our goal is to discover new NPM oxides for artificial NH3 synthesis via electrocatalytic N2 fixation. Here, we show that Y2O3 nanosheet is an active NRR electrocatalyst at ambient conditions. This catalyst is capable of attaining a NH3 yield of 1.06×10–10 mol s– 1

cm–2 and a high Faradaic efficiency (FE) of 2.53% in 0.1 M Na2SO4. Notably, it also owns excellent electrochemical durability and

stability in NRR electrocatalysis. Density functional theory (DFT) calculations review that the potential determining-step of the electrochemical NRR process is from *N2 to *N2H, following hydrogenation steps are feasible and it is easy to release NH3 molecules.

2. EXPERIMENTAL SECTION 2.1. Materials. Salicylic acid, nafion solution (5 wt%), sodium citrate, sodium hypochlorite (NaClO), sodium sulfate (Na2SO4), ammonium

chloride

(NH4Cl),

hydrazine

hydrate

(N2H4·H2O),

sodium

nitroferricyanide

(C5FeN6Na2O),

and

dimethylaminobenzaldehyde (C9H11NO) were procured from Aldrich. Yttrium acetate (Y(CH3COO)3), sodium hydroxide (NaOH), ethanol, and hydrochloric acid (HCl) were purchased from Aladdin. (Shanghai, China). The Millipore system was used to purify water. 2.2. Preparation of Y2O3 nanosheets. Y2O3 nanosheets were synthesized by hydrothermal followed by air annealing. Briefly, 16 mL of 0.1 M Y(CH3COO)3 were added to a beaker with 18 mL deionized water. After stirring about 1 h, the prepared 0.1M NaOH was added to the beaker and continuous agitating for 0.5h (pH=7). The mixture solution infunde a 50 mL autoclave. The autoclave was keep at 160 °C for 16 h. After cooled until ambient temperature, the white precipitates were centrifuged and washed with deionized water and ethanol for at least six times, and move to vacuum drying oven under 60 °C.

ACS Paragon Plus Environment


Page 4 of 11

2.3. Electrochemical measurements. Electrochemical measurements were carried out on a CHI 660E electrochemical analyzer (CHI Instruments, Shanghai) with three electrode system in a two-compartment cell separated by the Nafion 211 membrane under ambient condition, using carbon paper electrode (CPE) or Y2O3/CPE as working electrode, graphite rod as counter electrode, and Ag/AgCl as reference electrode. All potentials in this report were calibrated to reversible hydrogen electrode (RHE), using the equation: E (vs RHE) =E (vs Ag/AgCl) + 0.197 + 0.059 × pH. The ink was obtained as following: 5 mg catalyst powder was dispersed in a mixture solution of 40 μL Nafion (5 wt%), 0.48 ml ethanol and 0.48 ml deionized water with ultrasonic for 30 mins. 2.4. Computational method. Spin-polarized first-principles calculations based on the Density Functional Theory (DFT) were performed using the Vienna Ab initio Simulation Package (VASP)26–28 to investigate the NRR on the Y2O3 (111) surface. The Perdew-Burke-Ernzerhof (PBE) exchange-correlation functional within the generalized gradient approximation (GGA) was employed to describe the exchange-correlation energy.29 The projector-augmented-wave (PAW)30 method was adopted for the pseudopotentials. The energy cutoff for the plane wave basis expansion was set to 450 eV. The force on each atom smaller than 0.02 eV/Å was set for convergence criterion. Slab model was constructed by a unit cell with the lateral lattice constants of a=b=15.14 Å, and a vacuum region of 20 Å perpendicular to the surface to avoid the interaction between the slab and its imaging configuration. A Gaussian smearing for the occupations was used with a smearing width of 0.01 eV. The sampling in the Brillouin zone was set with 3×3×1 with the Monkhorst-Pack method.31 The Y2O3 (111) surface is a stack of O-Y-O sandwiches with oxygen terminations. In order to build the surface model with suitable atomic layers, the surface energies of the model with different atomic layers were calculated by: Esurf = ( Etot ―n ∗ Ebulk)/2A , where Etot and Ebulk is the DFT total energies of slab model and bulk, respectively. n denotes the ratio of the atom numbers of the slab with respect to that of the bulk, and A represents the surface area of the slab model. Our calculations yield the values of 0.056 and 0.055 eV/Å2 for the slabs with two and three O-Y-O sandwiches, respectively, indicating that the slab with two atomic sandwiches is thick enough for the following calculations. The sampling in the Brillouin zone was set with 3×3×1 with the Monkhorst-Pack method.32 The free energies of the NRR steps were calculated using the equation:33 G = EDFT + EZPE ―TΔS, where EDFT is the DFT calculated total energy, EZPE is the zero-point vibration energy obtained by vibration analysis, and TΔS term is gotten from the database.

3. RESULTS AND DISCUSSION Y2O3 nanosheets were fabricated by air-annealing of hydrothermally obtained Y(OH)3 precursor. As seen from X-ray diffraction (XRD) patterns in Figure 1a. The blue curve represent precursor, which diffraction peaks can be well identified with the Y(OH)3 (JCPDS No. 83–2042). In contrast, the air-annealed product with different diffraction peaks (red curve) can be ascribed to Y2O3 (JCPDS No. 86–1107), demonstrating successful conversion of Y(OH)3 to Y2O3. As shown in Figure 1B, the morphology of Y(OH)3 is nanosheet from scanning electron microscopy (SEM) images. Compared with Y(OH)3, it is clearly seen that the nanosheet morphology of Y2O3 in SEM images was intact (Figure 1C). In Figure S1, Energy-dispersive X-ray (EDX) spectrum indicates the

existence of Y and O with 2:3 atomic ratios. Nanosheet feature for Y2O3 is further demonstrated through transmission electron microscopy (TEM) image, as shown in Figure 1D. In Figure 1E, the high-resolution TEM (HRTEM) picture reveals that Y2O3 has lattice fringe with an interplane spacing of 3.06 Å, which is well corresponding to the (222) plane of Y2O3. EDX elemental mapping (Figure 1F) analysis further suggests that all Y and O are evenly distributed in the nanosheet.


Page 5 of 11 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


Figure 1. (A) XRD patterns of Y(OH)3 and Y2O3. SEM images for (B) Y(OH)3 and (C) Y2O3 nanosheets. (D) TEM and (E) HRTEM image of Y2O3 nanosheets. (F) EDX maps of Y and O for Y2O3 nanosheet. (G) Raman spectrum of Y2O3. (H) XPS spectra of Y 3d binding energy region. (I) O 1s spectra for the Y2O3 nanosheet.

The Raman spectrum of Y2O3 is displayed in Figure 1G. The peaks at approximately 160, 473, and 466, cm–1 are assigned to the Fg+Ag vibrational modes of Y2O3.34–36 The survey spectrum of X-ray photoelectron spectroscopy (XPS) is shown in Figure S2, demonstrating the presence of Y and O elements in Y2O3 nanosheet. The high-resolution Y 3d XPS spectrum (Figure 1H) shows three binding energies (BEs) at 156.6, 158.6 and 160.2 eV which can be ascribed to Y 3d5/2 and Y 3d3/2, respectively, confirming the existence of Y3+.37,38 The O 1s region exhibits two BEs at 531.7 and 529.8 eV (Figure 1I), which can be assigned to O2– in Y2O3 nanosheet.39 According to the above analysis, Y2O3 has been successfully prepared.

Figure 2. (A) UV-Vis absorption spectra of the 0.1 M Na2SO4. (B) NH3 yields and (C) FEs for Y2O3/CPE. (D) Amounts of NH3 produced by Y2O3/CPE and blank CPE after 2-h electrolysis in N2 atmosphere.

NRR tests were performed in a gas-tight two-compartment electrocatalytic cell in 0.1 M Na2SO4 under ambient conditions. Y2O3 was combined with carbon paper electrode (Y2O3/CPE; Y2O3 loading: 0.1 mg) for electrochemical test. During electrochemical measurements, all potentials in this work were reported on a RHE scale, nitrogen was bubbled onto the cathode cell, and where the surface of catalyst can substantially contact with N2 and protons (H+) through the electrolyte to produce NH3. The product (NH3) in solution phase was detected by the method of indophenol blue to use spectrophotometrical,20 and another by-product (N2H4) was



Page 6 of 11

determined by the Watt and Chrisp method.40 The corresponding calibration curves are shown in Figure S3, S4. Figure 2A shows the UV-Vis results from various electrolytes of colored with indophenol indicator test in different potentials after electrocatalytic reaction for 2 h. As observed, the solution after electrolysis at –0.9 V shows the strongest absorption peak. In various potentials, the NH3 yields and FEs are exhibited in Figure 2B, C, respectively. As the negative potential mounted both NH3 yields and FEs increases until −0.9 V but decrease significantly over –0.9 V. The highest NRR rate locates at –0.9 V, where the yeild of NH3 is 1.06×10–10 mol s–1 cm–2 and the FE is 2.53%, comparing favourably to the behaviour of most reported NRR electrocatalysts, including Ru/C (3.44×10–12 mol s–1 cm–2, 0.28%),23 Mo nanofilm (3.09×10–11 mol s–1 cm–2, 0.72%).18 and Fe2O3–CNT (3.58×10–12 mol s–1 cm–2, 0.15%),20 A more detailed can be seen in Table S1. Selectivity is one key factor to assess the catalytic performance of catalysts.41–43 Of note, N2H4 is not detected (Figure S5) in the final product, indicating this catalyst possesses excellent selectivity. We also performed electrolysis at –0.9 V with Ar bubbled into and in open circuit potential in N2-saturated solution (Figure S6, 7), verifying NH3 is indeed generated via NRR by Y2O3. To evidence the deduction that the NH3 comes indeed from NRR process, Y2O3/CPE at –0.9 V with N2- and Arsaturated solutions alternating 2-h cycles, the test in Ar condition only provided vacant results, confirming NRR on the Y2O3 (Figure S8).Moreover, there is a linear correlation between the amount of produced NH3 and the time within 4-h electrolysis (Figure S9). Figure 2D displays the amount of NH3 formed in Y2O3/CPE and CPE at potential of -0.9 V after 2 h reaction. Clearly, CPE owns poor electrocatalytic NRR activity.

Figure 3. (A) Amperometric i-t curves of Y2O3/CPE for NRR. (B) Amperometric i-t curve for Y2O3/CPE. (C) NH3 yields and FEs under different N2 ﬂow rate. (D) Recycling test of Y2O3/CPE. The rest test occur at the potential of –0.9 V.

Furthermore, stability is another key factor to assess the catalytic performance of catalysts.44-51 Chrono-amperometry curves at corresponding potentials in N2-saturated 0.1 M Na2SO4 are shown in Figure 3A, which demonstrated that Y2O3 possesses stable electrocatalytic performance. We further performed long-term electrolysis for 20 h at potential of –0.9 V. As shown in Figure 3B, there is almost no decrease in current density. In Figure S10, TEM image of Y2O3 after long-term stability test show intact nanosheet morphology. Meanwhile XRD pattern evidenced that this catalyst after long-term electrocatalysis is still Y2O3 in nature. The change of electrocatalytic N2 reduction in various N2-flow rate was also investigated. It can be clearly seen that both NH3 yields and FEs have no significant influence after varying the flow velocity (Figure 3C), suggesting N2 diffusion in the solution is not the rate-determining step. A long-term cycling test was also performed to assess the electrochemical durability. As observed in Figure 3D, Y2O3/CPE shows negligible difference in NH3 yields and FEs during six cycles, demonstrating its superior electrochemical durability.


Page 7 of 11 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


Figure 4. (A) Free energy diagram for N2 reduction reaction process. An asterisk (*) denotes as the adsorption state. The competitive process is shown in orange line. (B) Charge density difference of the adsorbed system of *N2 and *NNH. The isosurface level is 0.0005e/Å3. Yellow and blue isosurfaces are represented as electron donation and accumulation, respectively.

We performed DFT calculations to gain insight into the catalytic mechanism. As shown in Figure 4A, the free energy profile of NRR steps on the Y2O3 (111) surface. At the beginning, the Y atom on the outmost was physically adsorbed a free N2 molecule with the N-Y bond of 2.89 Å, yielding the adsorption energy of 0.16 eV. Energy profile presents that the first hydrogen atom combine to *N2 to form *N2H with the free energy change of 2.19 eV is the potential-determining step. The bond lengths of N-H, N-N and N-Y are 1.064, 1.181 and 2.701Å, respectively. The charge density differences defined as △ρ=ρ(*A)-ρ(*)-ρ(A) (A=adsorbate) of *N2 and *N2H configurations are visualized in Figure 4B. The charge transfer is rather limited between the catalyst surface and the adsorbates because of their weak interactions. The dissociation of the N-N bonds occurs in the first hydrogenation step, since lots of electrons accumulate at the N-H bond and the charge transfer around the N-Y region are enhanced. The effect of second hydrogen atom is possible to form *NHNH or *NNH2. Our calculations indicate that the formation of *NNH2 is slight uphill in free energy, while it is downhill in free energy of -0.64 eV to form *NHNH. Interestingly, *NHNH2 is the unique configuration when the third hydrogen atom was added to either *NHNH or *NNH2. The trial configuration *NNH3 is not stable and was converted to *NHNH2 upon optimization. Subsequently, the formation of *NH2NH2 is downhill with the free energy decrease of 0.72 eV. After that, and it is easy to add more hydrogen atoms and release *NH3 molecules since the free energies of the next reaction steps are downhill.

4. CONSLUSIONS In summary, Y2O3 nanosheet has been experimentally and theoretically verified as an efficient NPM electrocatalyst to enable the electrohydrogenation of N2 to NH3 under ambient environment. This catalyst is excellent in activity with NH3 yield of 1.06×10–10 mol s–1 cm–2 and a high FE of 2.53% as well as excellent electrochemical stability. DFT calculations further suggest that the potentialdetermining step of the NRR process is hydrogenation of *N2 to form *N2H with a free energy of 2.19 eV. This study not only



Page 8 of 11

provides us a high-performance catalyst for NH3 production, but would inspiring to deep develop Y-based nanocatalysts for artificial N2 fixation.

■ SUPPORTING INFORMATION Figure S1 showing the EDX spectrum of Y2O3; Figure S2 showing the XPS survey spectrum for Y2O3 nanosheets; Figure S3 (A) showing UV-Vis spectra of indophenol assays of NH3 concentrations incubated for 1 h at room temperature; Figure S3 (B) showing the calibration curve used for estimation of NH3 concentrations; Figure S4 (A) showing UV-Vis absorption spectra of various N2H4 concentrations after incubated for 20 min at room temperature; Figure S4 (B) showing calibration curve used for estimation of N2H4 concentrations; Figure S5 showing UV-Vis spectra after electrolysis coloured by para-(dimethylamino) benzaldehyde indicator; Figure S6 showing UV-Vis spectra before and after 2 h electrolysis at -0.9 V under Ar atmosphere; Figure S7 showing UV-Vis spectra t before and after 2 h electrolysis at open circuit under ambient condition; Figure S8 showing the NH3 yields for Y2O3/CPE at N2- and Ar-saturated electrolyte; Figure S9 showing the curve of ammonia production vs. reaction time. Figure S10 (A) showing the TEM image of Y2O3 after stability test; Figure S10 (B) the XRD patterns for CP and Y2O3/CP after long-term electrolytic reaction in 0.1 M Na2SO4; Table S1 listing the comparison of the NH3 electrosynthesis activity for Y2O3 nanosheet with other NRR catalysts under ambient conditions.

■ AUTHOR INFORMATION Corresponding Author *E-mail: [email protected] (Q. W.) *E-mail:[email protected] (B. L.) ORCID Qin Wei: 0000-0002-3034-8046

Notes The authors declare no competing financial interest.

■ ACKNOWLEDGMENTS This work was supported by the National Key Scientific Instrument and Equipment Development Project of China (No. 21627809), the National Natural Science Foundation of China (No. 21575050).

■ REFERENCES (1) Service, R. F.; New Recipe Produces Ammonia From Air, Water, and Sunlight. Science 2014, 345, 610. (2) Smil, V.; Detonator of the Population Explosion. Nature 1999, 400, 415. (3) Schlögl, R.; Catalytic Synthesis of Ammonia—A “Never-Ending Story”? Angew. Chem. Int. Ed. 2003, 42, 2004–2008. (4) Catalytic Ammonia Synthesis-Fundamentals and Practice (Ed. J. R. Jennings), Springer Science+Business Media, New York, 1991, pp. (5) Vegge, T. Sørensen, R. Z.; Klerke, A.; Hummelshøj, J. S.; Johannessen, T.; Nørskov, J. K.; Christensen, C. H.; Indirect Hydrogen Storage in Metal Ammines, In Solid state hydrogen storage: Materials and chemistry, British Welding Research Association, 2008, pp. 533–568. (6) Brown, K. A.; Harris, D. F.; Wilker, M. B.; Rasmussen, A.; Khadka, N.; Hamby, H.; Keable, S.; Dukovic, G.; Peters, J. W.; Seefeldt, L. C.; King, P. W.; Light-Driven Dinitrogen Reduction Catalyzed by a CdS:nitrogenase MoFe Protein Biohybrid. Science 2016, 352, 448– 450. (7) Singh, A. R.; Rohr, B. A.; Schwalbe, J. A.; Cargnello, M.; Chan, K.; Jaramillo, T. F.; Chorkendorff, I.; Nørskov, J. K.; Electrochemical Ammonia Synthesis–The Selectivity Challenge. ACS Catal. 2017, 7, 706–709.


Page 9 of 11 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


(8) Ham, C. J. M.; Koper, M. T. M.; Hetterscheid, D. G. H.; Challenges in Reduction of Dinitrogen by Proton and Electron Transfer. Chem. Soc. Rev. 2014, 43, 5183–5191. (9) Shipman, M. A.; Symes, M. D.; Recent Progress towards the Electrosynthesis of Ammonia from Sustainable Resources. Catal. Today 2017, 286, 57–68. (10) Kyriakou, V.; Garagounis, I.; Vasileiou, E.; Vourros, A.; Stoukides, M.; Progress in the Electrochemical Synthesis of Ammonia. Catal. Today 2017, 286, 2–13. (11) Renner, J. N.; Greenlee, L. F.; Ayres, K. E.; Herring, A. M.; Electrochemical Synthesis of Ammonia: A Low Pressure, Low Temperature Approach. Electrochem. Soc. Interface 2015, 24, 51–57. (12) Seh, Z. W.; Kibsgaard, J.; Dickens, C. F.; Chorkendorff, I.; Nørskov, J. K.; Jaramillo, T. F.; Combining Theory and Experiment in Electrocatalysis: Insights into Materials Design. Science 2017, 355, 6321–6336. (13) Guo, C.; Ran, J.; Vasileff, A.; Qiao, S.; Rational Design of Electrocatalysts and Photo (electro) Catalysts for Nitrogen Reduction to Ammonia (NH3) under Ambient Conditions. Energy Environ. Sci. 2018, 11, 45–56. (14) Cao, N.; Zheng, G.; Aqueous Electrocatalytic N2 Reduction under Ambient Conditions. Nano Res. 2018, 11, 2992–3008. (15) Bao, D.; Zhang, Q.; Meng, F.; Zhong, X.; Shi, M.; Yan, J.; Jiang, Q.; Zhang, X.; Electrochemical Reduction of N2 under Ambient Conditions for Artifcial N2 Fixation and Renewable Energy Storage Using N2/NH3 Cycle. Adv. Mater. 2017, 29, 1604799. (16) Liu, H.; Han, S.; Zhao, Y.; Zhu, Y.; Tian, X.; Zeng, J.; Jiang, J.; Xia, B.; Chen, Y.; Surfactant-Free Atomically Ultrathin Rhodium Nanosheet Nanoassemblies for Efficient Nitrogen Electroreduction. J. Mater. Chem. A 2018, 6, 3211–3217. (17) Kugler, K.; Luhn, M.; Schramm, J.A.; Rahimi, K.; Wessling, M.; Galvanic Deposition of Rh and Ru on Randomly Structured Ti felts for the Electrochemical NH3 Synthesis. Phys. Chem. Chem. Phys. 2015, 17, 3768–3782. (18) Yang, D.; Chen, T.; Wang, Z.; Electrochemical Reduction of Aqueous Nitrogen (N2) at a Low Overpotential on (110)-Oriented Mo Nanofilm. J. Mater. Chem. A 2017, 5, 18967–18971. (19) Lv, C.; Yan, C.; Chen, G.; Ding, Y.; Sun, J.; Zhou, Y.; Yu, G.; An Amorphous Noble-Metal-Free Electrocatalyst that Enables Nitrogen Fixation under Ambient Conditions. Angew. Chem. Int. Ed. 2018, 57, 6073–6076. (20) Chen, S.; Perathoner, S.; Ampelli, C.; Mebrahtu, C.; Su, D.; Centi, G.; Electrocatalytic Synthesis of Ammonia at Room Temperature and Atmospheric Pressure from Water and Nitrogen on a CarbonNanotube-Based Electrocatalyst. Angew. Chem. Int. Ed. 2017, 56, 2699– 2703. (21) Kong, J.; Lim, A.; Yoon, C.; Jang, J. H.; Ham, H. C.; Han, J.; Nam, S.; Kim, D.; Sung, Y. E.; Choi, J.; Park, H. S.; Electrochemical Synthesis of NH3 at Low Temperature and Atmospheric Pressure Using a γ-Fe2O3 Catalyst. ACS Sustainable Chem. Eng. 2017, 5, 10986– 10995. (22) Li, X.; Li, T.; Ma, Y.; Wei, Q.; Qiu, W.; Guo, H.; Shi, X.; Zhang, P.; Asiri, A.; Chen, L.; Tang, B.; Sun, X.; Boosted Electrocatalytic N2 Reduction to NH3 by Defect-Rich MoS2 Nanoflower. Adv. Energy Mater. 2018, DOI: 10.1002/aenm.201801357. (23) Kordali, V.; Kyriacou, G.; Lambrou, C.; Electrochemical Synthesis of Ammonia at Atmospheric Pressure and Low Temperature in a Solid Polymer Electrolyte Cell. Chem. Commun. 2000, 17, 1673–1674. (24) Zhang, L.; Ji, X.; Ren, X.; Ma, Y.; Shi, X.; Asiri, A. M.; Chen, L.; Tang, B.; Sun, X.; Electrochemical Ammonia Synthesis via Nitrogen Reduction Reaction on a MoS2 Catalyst: Theoretical and Experimental Studies. Adv. Mater. 2018, 30, 1800191. (25) Qiu, W.; Xie, X.; Qiu, J.; Fang, W.; Liang, R.; Ren, X.; Ji, X.; Cui, G.; Asiri, A.; Cui, G.; Tang, B.; Sun, X.; High-Performance Artificial Nitrogen Fixation at Ambient Conditions Using a Metal-Free Electrocatalyst. Nat. Commun. 2018, 9, 3485. (26) Kresse, G.; Furthmuller, Efficiency of Ab-Initio Total Energy Calculations for Metals and Semiconductors Using a Plane-Wave Basis Set. J. Comp. Mater. Sci. 1996, 6, 15–50. (27) Kresse, G.; Furthmuller, Efficient Iterative Schemes for Ab Initio Total-Energy Calculations Using a Plane-Wave Basis Set. J. Phys. Rev. B 1996, 54, 11169–11186. (28) Kresse, G.; Hafner, Ab Initio Molecular-Dynamics Simulation of the Liquid-Metal–Amorphous-Semiconductor Transition in Germanium. J. Phys. Rev. B 1994, 49, 14251–14269. (29) Perdew, J.; Chevary, J. A.; Vosko, S. H.; Jackson, K.; Pederson, M. D.; Singh, J.; Fiolhais, C.; Atoms, Molecules, Solids, and Surfaces: Applications of the Generalized Gradient Approximation for Exchange and Correlation. Phys. Rev. B 1992, 46, 6671–6687. (30) Blochl, P. E.; Projector Augmented-Wave Method. Phys. Rev. B 1994, 50, 17953–17979. (31) Monkhorst, H. J.; Pack, J. D.; Special Points for Brillonin-Zone Integrations. Phys. Rev. B 1976, 13, 5188–5192. (32) Monkhorst, H. J.; Pack, J. D.; Special Points for Brillouin-Zone Integrations. Phys. Rev. B 1976, 13, 5188–5192. (33) Skulason, E.; Bligaard, T.; Gudmundsdottir, S.; Studt, F.; Rossmeisl, J.; Abild-Pedersen, F.; Vegge, T.; Jonsson, H.; Norskov, J. K.; A Theoretical Evaluation of Possible Transition Metal Electro-Catalysts for N2 Reduction. Phys. Chem. Chem. Phys. 2012, 14, 1235–1245. (34) Guo, H.; Zhang, W.; Lou, L.; Brioude, A.; Mugnier, J.; Structure and Optical Properties of Rare Earth Doped Y2O3 Waveguide Films Derived by Sol–Gel Process. Thin Solid Films 2004, 458, 274–280.



Page 10 of 11

(35) Repelin, Y.; Proust, C.; Husson, E.; Beny, J. M.; Vibrational Spectroscopy of the C-Form of Yttrium Sesquioxide. J. Solid State Chem. 1995, 118, 163–169. (36) Barve, S. A.; Jagannath, Mithal, N.; Deo, M. N.; Chand, N.; Bhanage, B. M.; Gantayet, L. M.; Patil, D. S.; Microwave ECR Plasma CVD of Cubic Y2O3 Coatings and Their Characterization. Surf. Coat. Tech. 2010, 204, 3167–3172. (37) Wang, S. Y.; Lu, Z. H.; Preparation of Y2O3 Thin Films Deposited by Pulse Ultrasonic Spray Pyrolysis. Mater. Chem. Phys. 2003, 78, 542–545. (38) Cho, M. H.; Ko, D. H.; Jeong, K.; Whangbo, S. W.; Whang, C. N.; Choi, S. C.; Cho, S. J.; Structural Transition of Crystalline Y2O3 Film on Si(111) with Substrate Temperature. Thin Solid Films 1999, 349, 266–269. (39) Pan, T. M.; Liao, K. M.; Structural Properties and Sensing Characteristics of Y2O3 Sensing Membrane for pH-ISFET. Sens. Actuators B 2007, 127, 480–485. (40) Watt, G. W.; Chrisp, J. D.; A Spectrophotometric Method for the Determination of Hydrazine. Anal. Chem. 1952, 24, 2006–2008. (41) Ren, X.; Cui, G.; Chen, L.; Xie, F.; Wei, Q.; Tian, Z.; Sun, X.; Electrochemical N2 fixation to NH3 Under Ambient Conditions: Mo2N Nanorod as a Highly Efficient and Selective Catalyst. Chem. Commun. 2018, 54, 8474–8477. (42) Han, J.; Liu, Z.; Ma, Y.; Cui, G.; Xie, F.; Wang, F.; Wu, Y.; Gao, S.; Xu, Y.; Sun, X.; Ambient N2 Fixation to NH3 at Ambient Conditions: Using Nb2O5 Nanofiber as a High-Performance Electrocatalyst. Nano Energy 2018, 52, 264–270. (43) Zhang, Y.; Qiu, W.; Ma, Y.; Luo, Y.; Tian, Z.; Cui, G.; Xie, F.; Chen, L.; Li, T.; Sun, X.; High-Performance Electrohydrogenation of N2 to NH3 Catalyzed by Multishelled Hollow Cr2O3 Microspheres at Ambient Conditions. ACS Catal. 2018, 8, 8540–8544. (44) Ren, X.; Ge, R.; Zhang, Y.; Liu, D.; Wu, D.; Sun, X.; Du, B.; Wei, Q.; Cobalt-Borate Nanowire Array as a High-Performance Catalyst for Oxygen Evolution Reaction in Near-Neutral Media. J. Mater. Chem. A. 2017, 5, 7291–7294. (45) Ren, X.; Wu, D.; Ge, R.; Sun, X.; Ma, H.; Yan, T.; Zhang, Y.; Du, B.; Wei, Q.; Chen, L.; Self-Supported CoMoS4 Nanosheet Array as an Efficient Catalyst for Hydrogen Evolution Reaction at Neutral pH. Nano Res. 2018, 11, 2024–2033. (46) Wu, D.; Wei, Y.; Ren, X.; Ji, X.; Liu, Y.; Guo, X.; Liu, Z.; Asiri, A.; Wei, Q.; Sun, X.; Co(OH)2 Nanoparticles-Encapsulating Conductive Nanowires Array: Room-Temperature Electrochemical Preparation for High-Performance Water Oxidation Electrocatalysis. Adv. Mater. 2018, 30, 1705366–1705372. (47) Ren, X.; Ji, X.; Wei, Y.; Wu, D.; Zhang, Y.; Ma, M.; Liu, Z.; Asiri, A.; Wei, Q.; Sun, X.; In Situ Electrochemical Development of Copper Oxide Nanocatalysts Within a TCNQ Nanowire Array: a Highly Conductive Electrocatalyst for the Oxygen Evolution Reaction. Chem. Commun. 2018, 54, 1425–1428. (48) Wei, Y.; Ren, X.; Ma, H.; Sun, X.; Zhang, Y.; Kuang, X.; Yan, T.; Ju, H.; Wu, D.; Wei, Q.; CoC2O4·2H2O Derived Co3O4 Nanorods Array: a High-Efficiency 1D Electrocatalyst for Alkaline Oxygen Evolution Reaction. Chem. Commun. 2018, 54, 1533–1536. (49) Li, X.; Sun, X.; Ren, X.; Wu, D.; Kuang, X.; Ma, H.; Yan, T.; Wei, Q.; Porous Fe–N-Codoped Carbon Microspheres: An Efficient and Durable Electrocatalyst for Oxygen Reduction Reaction. Inorg. Chem. Front. 2018, 5, 2211–42217. (50) Zhao, J.; Ren, X.; Han, Q.; Fan, D.; Sun, X.; Kuang, X.; Wei, Q.; Wu, D.; Ultra-Thin Wrinkled NiOOH–NiCr2O4 Nanosheets on Ni Foam: an Advanced Catalytic Electrode for Oxygen Evolution Reaction. Chem. Commun. 2018, 54, 4987–4990. (51) Zhao, J.; Ren, X.; Ma, H.; Sun, X.; Zhang, Y.; Yan, T.; Wei, Q.; Wu, D.; Synthesis of Self-Supported Amorphous CoMoO4 Nanowire Array for Highly Efficient Hydrogen Evolution Reaction. ACS Sustainable Chem. Eng. 2017, 5, 10093–410098.


Page 11 of 11 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


For Table of Contents Only


Enabling Electrocatalytic N2 Reduction to NH3 by Y2O3 Nanosheet

Recommend Documents